1. Field of the Invention
The present invention relates generally to medical devices with porous layers and methods for making the same. More specifically, the invention relates to implantable medical devices having at least one porous layer, methods for making such devices and loading the porous layer with therapeutic agents. The porous layer may be used as a bonding interface for other coatings applied to the medical device, including drug-eluting coatings. The porous layer may have a random pore structure or an oriented or directional pore structure. The invention also relates to implantable medical devices having at least one porous layer that do not require loading with a therapeutic agent.
2. Description of the Related Art
Implantable medical devices are increasingly being used to deliver one or more therapeutic agents to a site within a body. Such agents may provide their own benefits to treatment and/or may enhance the efficacy of the implantable device. For example, much research has been conducted into the use of drug eluting stents for use in percutaneous transluminal coronary angioplasty (PTCA) procedures. Although some implantable devices are simply coated with one or more therapeutic agents, other devices include means for containing, attaching or otherwise holding therapeutic agents to provide the agents at a treatment location over a longer duration, in a controlled release manner, or the like.
Porous materials, for example, are commonly used in medical implants as reservoirs for the retention of therapeutic agents. Materials that have been used for this purpose include ceramics such as hydroxyapatites and porous alumina, as well as sintered metal powders. Polymeric materials such as poly(ethylene glycol)/poly(L-lactic acid) (PLGA) have also been used for this purpose.